The number and range of applications for magnetic field sensors is growing steadily, in the automotive industry in particular. Among other things, magnetic field measurement may be used for the non-contact, low-loss, and potential-free measurement of currents. Examples include the determination of electrical operating parameters of generators and electrical drives. In general, currents from the milliampere to the kiloampere range must be measured, which requires a measuring range of five to six orders of magnitude.
The devices known today measure magnetic fields of current conductors, for example, by using magnetic field sensors such as Hall sensors, bipolar magnetotransistors, magnetoresistive resistors, lateral magneto-FET structures, etc. A particularly sensitive component is the lateral magnetotransistor, the function of which is based on the asymmetrical current distribution generated by the magnetic field between two bipolar transistors.
For currents in the milliampere range, even such components reach the limits of their sensitivity due to the low magnetic fields, typically in the μT range. For that reason, in the related art, low magnetic fields are amplified by flux concentrators which make the magnetic fields stronger at the site of the magnetic field sensors through suitable shaping of the current conductors or through magnetic circuits made of highly permeable materials.